Combustion engine muffler



July 23', 1968 1-. B. MONK COMBUSTION ENGINE MUFFLER Filed June 28, 1967 I NVENTOR.

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United States Patent 3,393,767 COMBUSTION ENGINE MUFFLER Travis B. Monk, Rte. 1, Box 332, Mentone, Calif. 92359 Filed June 28, 1967, Ser. No. 649,648 1 Claim. (Cl. 181-67) ABSTRACT OF THE DISCLOSURE This invention improves upon prior proposed sound muffiing devices of the essentially smooth helical bafile type, by providing a combustion engine mufiler, the tubular shell of which contains an extended helical baflle specially formed to have radial corrugations of inwardly increasing depth, the effect of which is to increase the bafi ling and attenuation of the sound waves by deflecting some of the gas flow into a central through-passage defined by the inner bafiie edge, reentry of turbulent gas from that passage into the helical passage between the bafile turns being permitted by the corrugated configuration. Preferably the baflle is perforated outwardly of the corrugations to cause additional attenuation of the gas flow.

Summary of the invention I-leretofore it has been proposed to effect mufiling or silencing of audible gas stream pulsations by devices in the form of shells containing a helical baffle having essentially smooth surfaces contacted by the gas in traveling a helical path between the bafile turns, the effect of which has been largely to merely direct the gas flow in an extended helical course.

The present invention achieves additional baffling and gas attenuating effects in this same basic type of mufiler by a new and different helical bafile configuration according to which the metallic helix is deformed to have radial and preferably sequentially continuous radial corrugations of inwardly increasing depth and presenting surfaces so irregularized that the gas flow becomes bafiled or directed not only helically but generally radially in relation to a central through-passage defined by the inner edge of the baflle. Thus increased attenuation of the gas transmitted sound waves results from added turbulence in gas flow radially out of and into the helical passage, but without significant pressure drop through the mutiler.

The later illustrated baffle configuration presents a further practical manufacturing advantage in that formation of the corrugations permits cold rolling or shaping of the bafiie for outer edge conformance with a cylindrical shell.

As previously indicated additional gas attenuation may be achieved by perforating the baflle at spaced intervals, as by initially drilling the bafile sheet stock at locations such that when the sheet is helically deformed the perforations will be located outwardly of the corrugations.

These and various additional features and objects of the invention will more fully appear from the following detailed description of an illustrative embodiment shown by the accompanying drawing:

Brief description of the drawing FIG. 1 is a view showing the muffler in side elevation, a portion of the shell being broken away to expose the baffie;

FIG. 2 is an enlarged cross section on line 2-2 of FIG. 1; and

FIG. 3 is a fragmentary sectional enlargement of the shell and battle.

3,393,767 Patented July 23, 1968 Description of the preferred embodiments In reference first to the assembly appearing in FIG. 1, the muffler has an outer tubular shell 10, the longitudinal extent of which may vary, e.g. as between 1 to 2 feet depending upon the requirements of dependent engines or installations. Preferably the ends of the muffler shell are swaged or reduced at 11, one end being suitably connectable as by pipe or fitting indicated by the broken lines 12 with the engine exhaust manifold, and the outlet end with a tailpipe 13 although in some instances the tailpipe may be omitted.

The shell 10 contains a helical baffle 14 which, like the shell may be formed of heat resistive metal, the baffle extent being generally between and in terminal proximity to the swaged shell ends 11. The baffle is shown to be peripherally bonded to the shell at spaced intervals by welding or brazing at 15 through openings in the shell. Entering from the inlet 12 the engine exhaust gas travels both a helical path through the continuous spaces 16 between the bafile turns and within a central throughpassage 19, see FIG. 2 defined by the inner edge of the baflle.

The invention is primarily concerned with the baffle configuration particularly illustrated in FIG. 3 wherein the bafiie is shown to have uniformly spaced radial corrugations 17 produced by cold deformation of the baffle metal, the corrugations starting from radially outward locations along the helic strip and increasing as illustrated to a considerable depth at the inner edge 16a of the baffle as in the portions shown in FIG. 3. Thus the corrugations present baffling progressively projecting crests 17a and channels 17b, impinged against and swept by the gas stream throughout the course of its helical passage in the channel 16.

As previously indicated, additional attenuation is given the gas fiow by the formation of apertures 18 through the baffle outwardly from the corrugations 17, with which the apertures may be radially alined.

During its passage through the muflier the gas stream has lateral sweeping impingement against the corrugations 17 resulting in localized baffling of the gas and deflection of a portion through the corrugation channel 17b into the through-passage 19. Turbulence in the latter also tends to reversely displace some of the gas back into the helical space 16 and through the corrugation channels 171'). The total effect is productive of attenuation of the sound pulsations or waves in the gas stream, contributory to their elimination at audible level in the discharge gas. Presence of the apertures 18 through which the gas flow is restricted, further attenuates the gas flow so that the end result is a mufiler performance eliminative of high efliciency of all audible sounds.

I claim:

1. An engine muffler comprising a tubular shell, an extended helical baflle of single sheet metal thickness within the shell and having its tur-ns radially corrugated at increasing depth toward the inner edge of the baflie, said corrugations presenting deflective impingement surfaces about a central passage defined by the inner edge of the bafile to combustion gases being directed spirally between the bafile turns, said baflle having spirally spaced apertures radially outwardly beyond the corrugations.

References Cited FOREIGN PATENTS 1,087,417 8/1954 France.

266,706 3/1928 Great Britain. 422,004 1/ 1935 Great Britain. 426,897 4/ 1935 Great Britain.

ROBERT S. WARD, JR., Primary Examiner. 

